How can I stop my logo from stretching / being weird? (Blender 2.91.0)
I have seen your question and your issue, and It is quite common. Luckily, the solution is simple. Go to the UV editing section, before going there, remember to select the cylinder. Then select the face which is supposed to have the logo and carefully align it. For making it much more realistic, let the logo cover on of the faces but along with that, should cover a bit of the faces left and right to it. Hope it helps, if theres an issue with my solution, comment on my answer. I would also recommend going to this website to help you get started on stack exchange.
https://blender.stackexchange.com/help/how-to-ask
and
https://blender.stackexchange.com/tour
Cheerios,
Aster17